The US Federal Aviation Administration (FAA) has warned that some cordless electric tools can be hazardous in an aviation environment.
An FAA presentation describes a hanger accident in which a man using a brush-type cordless drill died in an explosion and fire when he loosened a fuel panel on a Cessna 414 from which the fuel had not been drained. It was not clear whether the explosion and fire occurred when fuel began to escape, or when the man attempted to replace the panel screws.
‘We can only speculate that maybe he was distracted and attempted to remove the fuel panel by mistake; all the underwing panels look the same on this aircraft and the fuel panels are not placarded,’ the presentation says.
Brush-type electric motors make and break electrical connections mechanically, and can produced sparks and electrical ‘noise’.
The FAA presentation stresses the need to use brushless tools certified as suitable for use in hazardous environments such as aviation. Brushless motors use electronic rather than mechanical switching, and thus avoid the risk of sparking.